Conventionally, a control device for controlling an electric motor of a compressor incorporates a power device such as IGBT and IPM (intelligent power module) having a self-protection function (e.g., see Patent Literature 1).
In a control device of an electric sealed compressor, an AC/DC converter converts an AC voltage into a DC voltage, a capacitor smooths the DC voltage and supplies the smoothed DC voltage to the IPM, and the IPM activates the electric motor of the sealed compressor.
The IPM includes a power module constituted by, for example, IGBT, an overcurrent detection circuit which is a self-protection function, an overheat detection circuit which is a self-protection function, and a control voltage abnormality detection circuit which is a self-protection function, and controls the power module in response to a control signal from, for example, a controller such as a microcontroller.
The IPM is configured such that the overcurrent detection circuit detects overcurrent, the overheat detection circuit detects overheat, and the control voltage abnormality detection circuit detects a voltage supplied to the IPM, which is outside an operational range. Upon detection of the abnormality, the IPM turns OFF the power module by the self-protection function to protect an internal device, and outputs an abnormality detection signal (Fo signal) to shut-off the operation of the power module from outside. Upon detection of the Fo signal, the microcontroller stops outputting all control signals to stop the operation of the IPM. In the above described manner, the IPM performs the self-protection operation to prevent heat generation and incorrect operation of the IPM and the electric motor of the compressor due to the overcurrent, the overheat, and the control voltage abnormality.